Justin Rose shot a third-round 70 to move within three shots of the lead at the Memorial tournament in Dublin, Ohio.
The Englishman was in a five-way tie for second on five under at the demanding Muirfield Village Golf Club after carding three birdies and an eagle.
It marked a good recovery after a second-round 70, but there was still work to do to catch leader Matthew Goggin.
The Australian, who started the day tied for the lead with Kenny Perry, carded a one-under-par 71 to end the day on eight-under 208.
Penny was back level with Rose, Mike Weir, Matt Kuchar and Jerry Kelly on 211.
Goggin built a three-shot lead with two birdies in the first three holes, before the threat of lightning stopped play for two hours, 25 minutes.
The delay seemed to hurt his momentum, as he made just one birdie in the remainder of the round – but not that they were easy to come by on a course with thick rough and slick greens.
But he kept his mistakes to a minimum, making only two bogeys, to end the day in a great position to win the Jack Nicklaus-hosted event.
Rose, boosted by an eagle at the par-five 15th, stayed in contention for his first tour victory.
“I would prefer to be leading by three, but three back is a great place to be,” he said.
“There’s really no pressure. I’m in a position where it’s win-win.”
Goggin, meanwhile, now believes he can defy expectations to win.
“Three shots in front, I expect to win,” he said.
But the 33-year-old Australian will be in turbulent, uncharted waters as he seeks his first victory in 186 starts on the PGA Tour.
Goggin fully expects one his five closest pursuers to make a run on Sunday.
“It’s not like we have a bunch of choppers behind me,” he said.
“Someone’s going to have a good day because they’re the best players in the world, so you can’t expect to go out and chop it around and cruise to victory.
“It’s just not going to happen. You’re going to have to play well, but the bonus is you’re not leading the tournament because you played poorly.”
Although Goggin has not won on tour, Perry was under no illusions about the task at hand.
“He’s going to be a hard man to catch tomorrow,” Perry said. “Mathew played great, struck the ball beautifully.”
Weir, who matched the day’s best score, earned a final round pairing with Goggin.
“I’m very happy with my round,” said the Canadian.
“I hit the shots I wanted most of the way around and more than anything I’m rolling a lot of nice putts in. I haven’t been doing that in a while, so that’s the biggest thing.”
Goggin was pleased with the start to his third round and is confident of taking his chance on the final day.
“Two birdies in the first three holes was a great way to start and I was pretty steady from then on,” he said. “I made a couple of bogeys and a birdie but I had some other good opportunities too but didn’t take advantage of them.
“It’s a tough course and if I can handle myself (Sunday) the same way I did today, I’m going to feel the same amount of pressure.
“It’s a great opportunity. You work the first three days to give yourself this sort of chance and now it’s there to be taken.”